MAX2741ETI+

EVALUATION KIT AVAILABLE MAX2741 Integrated L1-Band GPS Receiver TEMP RANGE PIN-PACKAGE -40°C to +85°C 28 Thin QFN-EP* VCC1 1 N.C. 2 RFIN 3 IFOUT- IFIN+ IFIN- N.C. N.C. Pin Configuration/Functional Diagram m x 5m 28 27 26 25 24 23 22 ∑ 33.6MHz LNA 1612.8MHz 0 /2 /96 4 VCC4 6 GND 7 ADC 200kHz VCO 3225.6MHz /R /192 16.8MHz MUX REF OSC SPI INTERFACE 21 SDO 20 N.C. 19 VCC5 18 GPSIF0 17 GPSIF1 16 GPSIF2 15 GPSCLK P.D. 8 9 10 11 12 13 14 REFCLK 5 /16128 XTAL VCC3 90 SHDN VCC2 MAX2741 SDI ●● In-Vehicle Navigation Systems (IVNS) ●● Telematics (Vehicle and Asset Tracking, Inventory Management) ●● Emergency Response Systems ●● Emergency Road-Side Assistance ●● Location-Based Services/Internet (PDAs) ●● Digital Cameras/Camcorders ●● Recreational Handhelds/Walkie-Talkies ●● Geographical Information Systems (GIS) ●● Consumer Electronics (Location-Based Games) ●● Precision Timing 19-3559; Rev 1; 5/14 PART MAX2741ETI CS Applications Ordering Information m 5 m -PIN TQ FN 28 The receiver runs from a 2.7V to 3.0V supply, and draws only 30mA when active. It is offered in a 28-pin thin QFN package, and is specified for -40°C to +85°C at 3V. ●● Clock Output for Baseband Processor IFOUT+ The integrated synthesizer offers the flexibility in frequency planning to allow a single board design to be employed for reference frequencies from 2MHz to 26MHz. The integrated reference oscillator allows either TCXO or crystal operation. ●● Supports All Popular Handset Reference Frequencies Up to 26MHz ●● 4.7dB Cascaded Noise Figure ●● 80dB Cascaded Gain ●● Tolerates -90dBm In-Band Jammer ●● Tolerates +13dBm CDMA Out-of-Band Jammer at Device Input ●● Integrated Synthesizer and VCO ●● Integrated 2- or 3-Bit ADC ●● 50dB IF AGC Range ●● Small 28-Pin Thin QFN Package ●● SPI Control Interface SCLK This dual-conversion receiver downconverts the 1575.42MHz GPS signal to a 37.38MHz first IF, and then a 3.78MHz second IF. An integrated 2- or 3-bit ADC (1-bit SIGN, 1- or 2-bit MAG selectable) samples the second IF and outputs the digitized signals to the baseband processor. Features VCC6 The MAX2741 L1-band GPS receiver IC offers a high-performance, compact solution for mobile handsets and PDA applications. Total voltage gain of 80dB and a 4.7dB cascaded noise figure can provide receiver sensitivity for applications requiring -185dBW for indoor tracking solutions. FILT General Description MAX2741 Integrated L1-Band GPS Receiver Absolute Maximum Ratings VCC Pins to GND..................................................-0.3V to +3.3V VCC Pins to Each Other........................................-0.3V to +0.3V FILT to GND.............................................. -0.3V to (VCC + 0.3V) CMOS Inputs to GND (SHDN, SCLK, CS, SDI)............................................... +0.3V to (VCC + 0.3V) CMOS Outputs to GND (CLKOUT, GPSIF_, SDO)....................................... -0.3V to (VCC + 0.3V) RFIN to GND............................................. -0.3V to (VCC + 0.3V) First IF Filter I/O to GND (IFOUT±, IFIN±)......-0.3V to (VCC + 0.3V) Crystal Inputs to GND (XTAL, REFCLK).........-0.3V to (VCC + 0.3V) Maximum RF Input Power...................................................0dBm Continuous Power Dissipation (TA = +85°C) 28-Pin Thin QFN (derate 20.8mW/°C above +70°C).....1000mW Operating Temperature Range............................ -40°C to +85°C Junction Temperature.......................................................+150°C Storage Temperature Range............................. -65°C to +160°C Lead Temperature (soldering, 10s).................................. +300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. CAUTION! ESD SENSITIVE DEVICE DC Electrical Characteristics (Operating conditions (unless otherwise specified): VCC = 2.7V to 3.0V; REFCLK driven with 10MHz sinusoid, 1.2VP-P; registers set according to mode; no RF input signal; digital baseband outputs left open; TA = -40°C to +85°C. Typical values are measured at VCC = 2.75V, TA = +25°C.) PARAMETER CONDITIONS Supply Voltage Supply Current MIN TYP 2.7 Normal operation (TA = +25°C) 30 Standby (VSHDN = VIL, SYNTH:D8 = 0) 0.7 MAX UNITS 3.0 V 42 VCC 0.1 Input-Logic High Threshold V Input-Logic Low Threshold Input-Logic High/Low Current -10 Output-Logic High ILOAD = 100µA Output-Logic Low ILOAD = 100µA mA 0.1 V +10 µA VCC 0.3 V 0.3 V AC Electrical Characteristics (Operating conditions (unless otherwise specified): VCC = 2.7V to 3.0V for TA = -40°C to +85°C; REFCLK driven at 10MHz sinusoid, 1.2VP-P; registers set according to mode; using the Typical Application Circuit; CW RF signal at 1575.42MHz. Typical values are measured at VCC = 2.75V, TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS 1st CONVERSION STAGE (RF TO 1st IF) RF Frequency L1-band RF Conversion Gain (Note 1) Noise Figure Mid-gain (CONFIG1:D4–D0 = 10000) Input IP3 (Note 2) RF Image Rejection (Notes 3, 4) LO Leakage at RF LO to RFIN pin www.maximintegrated.com 1575.42 15 20 21 MHz 32 dB 4.7 dB -30 dBm 35 dB -90 dBm Maxim Integrated │  2 MAX2741 Integrated L1-Band GPS Receiver AC Electrical Characteristics (continued) (Operating conditions (unless otherwise specified): VCC = 2.7V to 3.0V for TA = -40°C to +85°C; REFCLK driven at 10MHz sinusoid, 1.2VP-P; registers set according to mode; using the Typical Application Circuit; CW RF signal at 1575.42MHz. Typical values are measured at VCC = 2.75V, TA = +25°C.) PARAMETER CONDITIONS MIN TYP MAX UNITS 2nd CONVERSION STAGE (1st IF TO ADC INPUT) 1st IF Frequency Conversion Gain At IFOUT Max gain (CONFIG1:D4–D0 = 11111) (Note 1) 37.38 48 61 MHz 74 dB Min gain (CONFIG1:D4–D0 = 00000) (Note 1) 10 dB Input IP3 1st conversion (Note 5) -36 dBm Noise Figure Max gain (CONFIG1:D4–D0 = 11111) 12 dB Real 0.40 mS Imaginary 1.5 pF Real 0.40 mS Imaginary 0.15 pF (SYNTH:D13–D10 = 1111) 2.9 (SYNTH:D13–D10 = 0000) 7.7 ICP_OH PLL charge-pump source current 75 µA ICP_OL PLL charge-pump sink current -100 µA Closed-Loop Phase Noise At 1kHz offset -55 dBc/Hz Comparison Spurs At ±200kHz offset -44 dBc/Hz Reference Oscillator Frequency Sinusoid (Note 1) 2 REF Input Voltage Level Sinusoid (Note 1) 0.6 VCO Coarse Tune Range Programmable (CONFIG1:D7 to D5 = 000 to 111) (Note 1) IF Output Port Admittance IF Input Port Admittance LPF -3dB Corner Frequency MHz SYNTHESIZER 10 26 MHz 2.2 VP-P 240 MHz 1 MHz DIGITAL I/O SPI Clock Frequency Note Note Note Note Note 1: Production tested for +25°C and +85°C, guaranteed by design and characterization for -40°C. 2: Test tones at 1575.8MHz and 1576.8MHz at -60dBm/tone. 3: Guaranteed by design and characterization. 4: Image frequency is 1575.42MHz + 2(fIF) = 1650.18MHz 5: Test tones at 37.38MHz and 36.88MHz at -50dBm/tone. www.maximintegrated.com Maxim Integrated │  3 MAX2741 Integrated L1-Band GPS Receiver Pin Description PIN NAME 1 VCC1 LNA Supply Connection. External RF bypass capacitor to ground required. FUNCTION 2, 20, 22, 23 N.C. Reserved. Make no connections to this pin. 3 RFIN LNA Input. Connect to GPS antenna through a bandpass filter. This input requires an external matching network to match to 50Ω. AC-couple to this pin. 4 VCC2 VCO Supply Connection. External RF bypass capacitor to ground required. 5 VCC3 CML Supply Connection. External RF bypass capacitor to ground required. 6 VCC4 Digital Logic and PLL Supply Connection. External RF bypass capacitor to digital ground required. 7 GND Ground. Connect to PC board digital ground plane. 8 FILT PLL Loop Filter Connection. This is the output of the phase detector’s charge pump. Use the recommended filter on EV kit for optimal phase noise and lock time. 9 SCLK SPI Clock Input (CMOS) 10 CS SPI Chip-Select Input (CMOS, Active Low) 11 SDI SPI Data Input (CMOS) 12 SHDN Full IC Power-Down. This shutdown pin disables the on-chip oscillator and the rest of the IC. To keep the oscillator running, use the software shutdown (SYNTH:D8); (CMOS, active high). 13 XTAL Crystal Oscillator Feedback Capacitor Connection 14 REFCLK Reference Clock Input for PLL. Drive with 1.2VP-P when using TCXO module. 15 GPSCLK GPS Clock Output to Baseband. This is the clock used by the ADC to sample the GPS data (CMOS). 16 GPSIF2 Sampled IF Output, Bit 2 (CMOS). See Table 5. 17 GPSIF1 Sampled IF Output, Bit 1 (CMOS). See Table 5. 18 GPSIF0 Sampled IF Output, Bit 0 (CMOS). See Table 5. 19 VCC5 IF Supply Connection. External RF bypass capacitor to ground required. 21 SDO SPI Data Output (CMOS) 24 IFIN- 1st IF Input (Inverting). Connect this 2.5kΩ differentially terminated input to the 1st IF filter’s (-) output. 25 IFIN+ 1st IF Input (Noninverting). Connect this 2.5kΩ differentially terminated input to the 1st IF filter’s (+) output. 26 IFOUT- 1st IF Output (Inverting). Connect this 2.4kΩ differential output to the 1st IF filter’s (-) input. 27 IFOUT+ 1st IF Output (Noninverting). Connect this 2.4kΩ differential output to the 1st IF filter’s (+) input. 28 VCC6 RF Image-Reject Mixer Supply. External RF bypass capacitor to ground required. Exposed Paddle GND RF Ground. Ultra-low inductance connection to ground. Place several vias to PC board ground plane. www.maximintegrated.com Maxim Integrated │  4 MAX2741 Detailed Description The MAX2741 GPS offers a high-performance superheterodyne receiver solution for low-power mobile devices, with the benefit of using the system’s existing clock reference. This receiver is ideal for integration into mobile phone handsets using common reference frequencies such as 10.0, 13.0, 14.4, 19.2, 20.0, and 26.0MHz. The only external components required are the GPS RF filter, an IF filter (typically designed from inexpensive discretes), a three-component PLL loop filter, and a few other resistors and capacitors. The MAX2741 integrates the reference oscillator core, the VCO and its tank, the synthesizer, a 1- to 3-bit ADC, and all signal path blocks except for the 1st IF filter. The typical application area for the receiver is less than 2cm. RF/1st Conversion Stage (Front-End) The MAX2741 RF front-end LNA and mixer are the most important in the signal path. This stage sets the noise figure for the receiver, defining the sensitivity, and mixes the 1575.42MHz L1-band GPS signal down to a 1st IF of 37.38MHz. The LNA itself has an NF of approximately 1.5dB; the cascaded NF of the front-end (including the mixer) is approximately 4.7dB, and the cascaded gain is typically 21dB. The image-reject mixer is set up for a high-side injected RFLO (1612.80MHz), and offers typically better than 30dB rejection of the image noise (1650.18MHz). The -30dBm input 3rd-order intercept (IIP3) of the RF strip, in conjunction with the GPS IF filter, provides excellent outof-band interferer immunity. The 1st IF outputs (IFOUT±) are internally biased to approximately 2V, and have a differential source impedance of approximately 2.5kΩ. The IF filter can be implemented as a discrete L/C filter, or as a monolithic SAW or ceramic if one is available. IF/2nd Conversion Stage The 2nd conversion stage consists of an active mixer, a variable-gain amplifier (VGA), and a tunable lowpass filter. The IF mixer is configured for low-side LO injection for a 2nd IF of 3.78MHz. Total gain in this stage is 62dB, and the VGA offers 51dB of gain adjustment. The VGA is typically controlled by the baseband IC through the SPI interface to optimize the signal swing for digitization by the ADC. Integrated L1-Band GPS Receiver DC offset compensation at the ADC input is performed by an on-chip 4-bit DAC. This compensates for any DC error introduced by transistor mismatch in the differential stage driving the ADC input, allowing the downconverted GPS signal’s DC level to be centered within the threshold voltages of the ADC. ADC The on-chip ADC samples the down-converted GPS signal at the 2nd IF (3.78MHz). Sampled output is provided in either 2-bit (1-bit magnitude, 1-bit sign) or 3-bit (2-bit magnitude, 1-bit sign) formats, as determined by the ADC mode configuration bit (CONFIG1:D15); see Table 5 for details. The ADC sample clock (system GPS clock) is derived either directly from the reference clock (SYNTH:D9 = 1), or from an RFLO divide-by-96 block to provide a 16.8MHz sample clock (SYNTH:D9 = 0). The clock is available to the baseband processor at GPSCLK (pin 15). The sampled ADC data bits are available on pins 16, 17, and 18 (GPSIF2, GPSIF1, and GPSIF0). The functionality of the pins is different in each mode (2-bit vs. 3-bit)—see Table 5 in determining the interface connection for the application circuit. Synthesizer The MAX2741 integrates an integer-N synthesizer; all blocks except the loop filter are on-chip. The reference can be either a crystal (driven by the internal oscillator), or a TCXO module. The oscillator provides a 5pF load to the crystal. A TCXO module should provide a swing in the 0.6VP-P to 2.2VP-P range. The reference divider (/R) is programmable (SYNTH: D7–D0), and can accommodate reference frequencies up to 26MHz. The reference divider needs to be set so the comparison frequency (fCOMP) at the frequency/ phase detector is 200kHz. The VCO runs at twice the frequency of the RFLO; the RFLO is therefore generated from the VCO using a quadrature divide-by-2 block. The RF LO is fCOMP x 8064 (typically 1612.80MHz), and the 1st IF LO is fCOMP x 168 (typically 33.6MHz); the RF and IF LO division ratios are not adjustable. This configuration allows for the use of reference frequencies common to GSM, CDMA, TDMA, TD-SCDMA, and UMTS handsets: 9.6MHz (R = 48), 13.0MHz (R = 65), 14.4MHz (R = 72), 19.2MHz (R = 96), 26.0MHz (R = 130), etc. The on-chip lowpass filter has an adjustable cutoff frequency, programmable from 2.9MHz to 7.7MHz in 16 steps. This LPF further reduces out-of-band noise and band-limits the signal to the ADC, ensuring that the sampling process does not generate alias components. www.maximintegrated.com Maxim Integrated │  5 MAX2741 Integrated L1-Band GPS Receiver SPI Bus, Address and Bit Assignments MAX2741 7 8 9 FILT GND 6 SCLK VCC4 22nF 36kΩ 100pF Figure 1. Recommended 3rd-Order PLL Filter The VCO offers a bank of tuning capacitors that can be latched in/out to adjust the center frequency. Because the system does not require any RF LO frequency change (i.e., changing channels), the VCO varactor tuning gain is very low by design, which means the tuning range of the VCO is narrow. The coarse-tune capacitors in the tank circuit allow the system to adjust the VCO center frequency as needed to guarantee that the synthesizer can lock. In practice, process and temperature effects on VCO centering are negligible, and a coarse-tune setting of 110 (CONFIG:D7 to D5) will center the VCO tuning range correctly in virtually all cases. To aid in bench and prototype testing, the PFD offers out-of-lock-high and out-of-lock-low indicators, available in the SPI STATUS register (STATUS:D9 to D8). Use these flags to determine if the VCO tuning range needs to be adjusted higher or lower in the case where the PLL cannot lock. The PLL filter is the only external block of the synthesizer. The typical filter is a classic C-R-C two-pole shunt network on the tune line. Low phase noise is preferred at the expense of longer PLL settling times, so a low 10kHz to 20kHz loop bandwidth is used. The recommended PLL 10kHz filter implementation, with charge pump set to 200µA (CONFIG1:D10 = 1), is shown in Figure 1. The system/GPS clock is derived either directly from the reference oscillator, or synthesized from the RFLO (see the ADC section). This clock is used as the sampling clock for the on-chip ADC, and is seen at pin 15, GPSCLK. www.maximintegrated.com An SPI-compatible serial interface is used to program the MAX2741 for configuring the different operating modes. In addition, data can be read out of the MAX2741 for status and diagnostic use. The serial interface is controlled by four signals: SCLK (serial clock), CS (chip-select), SDI (data input), and SDO (data output). The control of the PLL, AGC, test, offset management, and block selection is performed through the SPI bus from the baseband controller. A 20-bit word, with the MSB (D15) being sent first, is clocked into a serial shift register when the chip-select signal is asserted low. The SPI bus has four control lines: serial clock (SCLK), chip-select (CS), data in (SDI), and data out (SDO). Enable SDO functionality by setting the digital test bus bits: CONFIG1:D9 to D8 = 01. The timing of the interface signals is shown in Figure 2 and Table 1 along with typical values for setup and hold time requirements. For best performance, the SPI bus should be configured during the startup initialization and then left with the optimum values in the registers. Any changes to the ADC and VGA bits during GPS signal processing may cause glitches and corrupt the analog signal path. Reading from the SPI bus does not interrupt GPS operation. tSETUPSS CS tEND tSETUPD SCLK tHDATA SDI LSB tPERIOD MSB Figure 2. SPI Timing Diagram Table 1. SPI Timing Requirements SYMBOL PARAMETER TYP VALUE UNITS tSETUPD Data to SCLK setup 20 ns tPERIOD SCLK period 100 ns tHDATA Data hold to SCLK 20 ns tSETUPSS CS to SCLK disable 20 ns tEND Falling SCLK to CS inactive 20 ns Maxim Integrated │  6 STATUS www.maximintegrated.com D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 XTAL Clock Selected Parity Reserved LPF Autocalibrate End LPF Autotune (MSB) LPF Autotune LPF Autotune LPF Autotune (LSB) D15 D14 D13 D12 D11 D10 Out-of-Lock (Low) LPF Tuning Word LPF Tuning Word LPF Tuning Word (LSB) XTAL Clock Select Standby PLL Ref Div Ratio (MSB) PLL Ref Div Ratio PLL Ref Div Ratio PLL Ref Div Ratio PLL Ref Div Ratio PLL Ref Div Ratio PLL Ref Div Ratio ADC Offset Control (MSB) ADC Offset Control (SIGN) Double ChargePump Current Digital Test Bus Mode Select (MSB) Digital Test Bus Mode Select (LSB) VCO Coarse Tuning Range (MSB) VCO Coarse Tuning Range VCO Coarse Tuning Range (LSB) AGC Gain (MSB) AGC Gain AGC Gain AGC Gain Drive VCO High Reserved Reserved Reserved Reserved Reserved Reserved Reserved Reserved Analog Test Mode Select Analog Test Mode Select Analog Test Mode Select Analog Test Mode Select PLL Ref Div Ratio (LSB) LPF Tuning Word (MSB) ADC Offset Control Drive VCO Low 1 0 0 AGC Gain (LSB) LPF Autotune Initiate ADC Offset Control (LSB) CONFIG 2 0 0 1 0 1 Analog Test Mode Select Reserved CONFIG 1 ADC Mode D15 D14 D13 D12 D11 D10 Out-of-Lock (High) Reserved Reserved Reserved Reserved REGISTER NAME Reserved SYNTH Reset CMOS REGISTER NAME Reserved MAX2741 Integrated L1-Band GPS Receiver Table 2. Register Address and Data Bit Assigments (Write) DATA ADDRESS D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 A3 A2 A1 A0 0 1 1 0 Table 3. Register Address and Data Bit Assigments (Read) DATA ADDRESS A3 A2 A1 A0 0 1 1 1 Maxim Integrated │  7 MAX2741 Integrated L1-Band GPS Receiver Detailed Register Definitions Table 4. Detailed Register Definition for Write Address 0100: SYNTH DATA BIT DEFAULT DESCRIPTION D15 1 Reserved D14 1 LPF Autotune Initiate: I = Initiate autotune, 0 = Manual tuning. D13–D10 0100 D9 1 XTAL Clock Select: 1 = External reference, 0 = Synthesized 16.8MHz. D8 0 Standby: 0 = Normal operating mode, 1 = Standby (oscillator remains active), but only if D9 = 1. D7–D0 01100000 LPF Tuning Word: 0000 ~ 7.7MHz, 1111 ~ 2.9MHz. Reference Division Ratio. Default 19.2MHz external reference (R = 96dec). R = fREF/200kHz. Table 5. Detailed Register Definition for Write Address 0101: CONFIG 1 DATA BIT DEFAULT D15 1 D14–D11 0000 DESCRIPTION ADC Mode. Select 1 for 1-bit magnitude and sign, select 0 for 2-bit magnitude and sign. 1: GPSIF2 = sign, GPSIF1 = magnitude, GPSIF0 = X 0: GPSIF2 = MSB magnitude, GPSIF1 = LSB magnitude, GPSIF0 = sign ADC Offset Control (approx 4mV/step): D14 = LSB, D12 = MSB, D11 = sign. D10 0 Double Charge-Pump Current: 0 = 100µA, 1 = 200µA. D9 to D8 00 Digital Test Bus Mode Select. See Table 9 for test-mode descriptions. D7 to D5 001 VCO Coarse Tuning Range. 000 = Lowest frequency, 111 = Highest frequency. D4–D0 11111 AGC Gain. Digital control of the AGC amplifier in the 2nd IF section. 00000 => min gain, 11111 => max gain (linear gain ~2.5dB per unit SPI word). Table 6. Detailed Register Definition for Write Address 0110: CONFIG 2 DATA BIT DEFAULT D15 1 Reset CMOS: 0 = Hold CMOS dividers in reset and PFD is tri-stated, 1 = Inactive. D14 1 Drive VCO Low: 0 = Active, forces VCO to lowest frequency. N.B. do not activate both D14 and D13 at the same time. D13 1 Drive VCO High: 0 = Active, forces VCO to highest frequency. N.B. do not activate both D14 and D13 at the same time. D12–D7 100000 D6 to D5 11 D4–D0 11111 www.maximintegrated.com DESCRIPTION Reserved Must be programmed to 11 Analog Test Mode Select: Reserved Maxim Integrated │  8 MAX2741 Integrated L1-Band GPS Receiver Table 7. Detailed Register Definition for Read Address 0111: STATUS DATA BIT DEFAULT D15–D10 XXXXXX DESCRIPTION D9 X Out-of-Lock (High Frequency): 1 = PLL is out of lock, VCO free-running at its highest frequency, 0 = Locked. D8 X Out-of-Lock (Low Frequency): 1 = PLL is out of lock, VCO free-running at its lowest frequency, 0 = Locked high. D7 1 XTAL Clock Selected: 1 = Synthesized 16.8MHz reference, 0 = External clock. D6 X Parity: 1 = Even, 0 = Odd. D5 X Reserved D4 X LPF Autotune End: 0 = Autotune run ended; 1 = Calibrating or manual tuning. D3–D0 XXXX Reserved LPF Autotune: 0000 ~ 7.7MHz; 1111 = 2.9MHz. Applications Information Fundamentally, the only application areas that require careful consideration are the LNA input match and the 1st IF filter. Of course, proper supply bypassing, grounding, and layout is required for reliable performance from any RF circuit. LNA Input Matching Input matching is critical for optimum noise figure and system sensitivity. Optimum source impedance (as seen from the LNA input) for lowest noise figure is 29Ω + j47Ω. Remember that optimum noise match and optimum gain match (return loss) do not occur simultaneously, so a good application circuit will sacrifice gain slightly in favor of reduced noise figure. Gain and noise circles are provided in Figure 3; S11 tabular data is provided in Table 8. G = Gmax - 1dB NF = NFmin + 0.2dB Table 8. MAX2741 S11 FREQ (MHz) S11 (MAG) S11 (°) 1100 0.874 -50.9 1200 0.867 -56.1 1300 0.859 -61.5 1400 0.842 -66.9 1500 0.821 -72.3 1550 0.809 -74.9 1560 0.806 -75.4 1570 0.804 -75.9 1575 0.803 -76.2 1580 0.801 -76.4 1590 0.799 -77.0 1600 0.796 -77.5 1650 0.783 -80.0 1700 0.768 -82.5 1800 0.739 -87.4 1900 0.708 -92.3 2000 0.677 -96.8 1st IF Interface and Filtering The typical application uses a 37.38MHz 1st IF, and employs an IF filter. The order of the filter should be tailored to suit the application—stand-alone GPS receivers will not require the channel-selection and stopband attenuation of GPS receivers that are integrated into other wireless handsets. Be sure that the filter topology provides DC-blocking for the IF I/O ports. Figure 3. Gain and Noise Circles for MAX2741 LNA Input www.maximintegrated.com Maxim Integrated │  9 MAX2741 Integrated L1-Band GPS Receiver 28 VCC1 N.C. RFIN VCC2 VCC3 VCC4 GND 27 26 25 24 N.C. N.C. IFIN- IFIN+ IFOUT- IFOUT+ VCC6 Typical Interface Diagram 23 22 1 21 2 20 3 19 MAX2741 4 18 5 17 6 16 7 15 SDO N.C. BASEBAND IC SDO SD1 VCC5 CS GPSIF0 SCLK GPSIF1 GPSIF0 GPSIF2 GPSCLK GPSIF1 GPSIF2 GPSCLK REFCLK 14 REFCLK 13 XTAL 12 SHDN 11 SDI 10 CS FILT 9 SCLK 8 Interface Summary All I/O connections are DC-coupled. Supply voltages as specified in the electrical specifications. RF I/O CONNECTION RFIN RECEIVER LNA Input RF BPF RF BPF Output IF I/O CONNECTION RECEIVER IF FILTER IFOUT+ 1st IF Output from Mixer (+) IF BPF Input, 2.5kΩ Differential IFOUT- 1st IF Output from Mixer (-) IF BPF Input, 2.5kΩ Differential IFIN+ 1st IF Input (+) IF BPF Input, 2.5kΩ Differential IFIN- 1st IF Input (-) IF BPF Input, 2.5kΩ Differential BASEBAND I/O CONNECTION RECEIVER BB IC/MAC SCLK CMOS Input CMOS Output CS CMOS Input CMOS Output SDI CMOS Input CMOS Output SDO CMOS Output CMOS Input CMOS Input CMOS Output GPSCLK SHDN CMOS Output CMOS Input GPSIF0 CMOS Output CMOS Input GPSIF1 CMOS Output CMOS Input GPSIF2 CMOS Output CMOS Input SYNTHESIZER I/O CONNECTION RECEIVER EXTERNAL COMPONENTS FILT PLL Phase-Detector Charge-Pump Output PLL Loop Filter XTAL Crystal Oscillator Feedback Feedback Capacitors External TCXO or Crystal Analog (also connected to REFCLK input to MAC) REFCLK www.maximintegrated.com Maxim Integrated │  10 MAX2741 Integrated L1-Band GPS Receiver Typical Application Circuit 28 VCC1 100pF 22pF N.C. 100pF VCC2 22pF 100pF VCC3 VCC4 IFIN- IFIN+ 5.6pF 25 24 39pF 680pF 23 ∑ 1 22 MAX2741 2 21 20 33.6MHz LNA 3 1612.8MHz 90 0 /2 19 /96 4 /16128 5 P.D. 17 /R /192 16.8MHz 6 18 ADC 200kHz VCO 3225.6MHz 100pF 100nF 680pF 26 680pF MUX 16 SPI DATA OUT TO BASEBAND PROCESSOR SDO N.C. VCC5 100pF VCC 1nF GPSIF0 GPSIF1 GPS DATA AND CLOCK TO BASEBAND PROCESSOR GPSIF2 100pF REF OSC SPI INTERFACE 7 9 SCLK FILT 8 10 11 15 12 22nF 13 GPSCLK 14 REFCLK GND XTAL 1nF 470µH SHDN VCC RFIN 2.2pF VCC VCC 6.2nH 470µH SDI GPS RF INPUT FROM GPS BPF 27 CS VCC IFOUT- IFOUT+ 22pF VCC6 100pF 5.6pF N.C. 39pF 680pF N.C. VCC 220pF 100pF 36kΩ SPI CLOCK AND DATA INTO BASEBAND PROCESSOR H/W SHUTDOWN LINE FROM BASEBAND PROCESSOR SYSTEM TCXO (2MHz TO 26MHz) Table 9. Digital Test-Mode-Select Description DIGITAL OUTPUT FUNCTION MODE REGISTER SETTING CONFIG1:D9 to D8 GPSIF2 GPSIF1 GPSIF0 3 11 SIGN LSB MSB 2 10 M COUNTER R COUNTER HANDSHAKE STATUS 1 01 CHARGE PUMP UP CHARGE PUMP DOWN SDO 0 00 CML CLOCK CALIBRATE LPF END XTL CLOCK SELECTED Digital Test Bus The digital test bus (DTB) is provided to allow for easy bench analysis of the digital workings of the receiver. www.maximintegrated.com Maxim Integrated │  11 MAX2741 Integrated L1-Band GPS Receiver Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN NO. 28 TQFN-EP T2855-3 21-0140 90-0023 www.maximintegrated.com Maxim Integrated │  12 MAX2741 Integrated L1-Band GPS Receiver Revision History REVISION NUMBER REVISION DATE 0 1/05 Initial release — 1 5/14 Removed automotive reference from Applications and General Description 1 DESCRIPTION PAGES CHANGED For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2014 Maxim Integrated Products, Inc. │  13